What is an “offshore account”?
From the perspective of the US, an “offshore account” is a financial account that is located outside the US. So, if you live in Calgary and have an account with the Bank of Montreal, this qualifies as “offshore”. (I doubt that very many U.S. citizens abroad view their day-to-day bank accounts as being “offshore”.)
US Citizens Abroad: For US citizens abroad, “offshore” bank and brokerage accounts are part of day-to-day life. There is still a requirement that they be reported.
US Citizens and Green Card Holders Resident in the US: Given the climate of the last few years, if you are resident in the US, and you have financial accounts (including bank, brokerage, etc.) outside the US, it is essential that you take immediate steps to bring the accounts into compliance. It is legal to have them. But they must be reported.
This is an issue that should be dealt with immediately! This must be discussed with a lawyer.